Abstract: Optical Time Domain Reflectometers (OTDRs) based on Rayleigh scattering detection, which are predominant in the market today, are incapable of providing the centimeter to millimeter scale optical length measurement accuracy that some customer applications require. New applications that are extremely sensitive to relative signal latency, high frequency trading for example, require length equalized optical interconnects accurate to ±0.25% of total cable length. All OTDR technologies also require the user to input the correct index of refraction (n) for the material under test, which varies with fiber type and manufacturer.
In this paper we present a new Correlation-based OTDR (C-OTDR), operating at the same wavelength as the running applications for multimode and single mode fiber, to provide sub-centimeter accurate optical length measurements of fiber optic channels. Environmental temperatures for fibers under test are varied to validate the measurement’s high resolution.